Senior officers aboard the oil tanker Willowy were extremely confused by what happened to their large ship on May 31. Their boat, along with 4 others were all sailing in circles.While sailing in the Atlantic Ocean, west of Cape Town, South Africa, the ships suddenly could no longer be steered in the right direction and no one could figure out why.Ruled out hypothesesAlthough they originally thought it was due to strong currents, this theory was ruled out because there were no such currents in that area at the time.According to RT, soon after, the officers recalled what had happened to boats in the South China Sea and the Strait of Hormuz, which was somewhat similar.However, in the case of those vessels, Sky News stated that the navigation failure was due to alleged, systematic manipulation of the GPS, to undermine the tracking system on all commercial ships.Known as AIS (Automated Identification System), it transmits unique identifiers for each vessel to other nearby vessels, including GPS location, direction, and speed.Although this last theory made more sense, the Willowy was very far from those areas, so this hypothesis doesn't hold up either.Getty ImagesCould it be the South Atlantic Anomaly?The European Space Agency has determined that the Earth's magnetic field is weakening, mainly in a large area that stretches from Africa to South America. This phenomenon was dubbed the 'South Atlantic Anomaly.'On the other hand, according to RT, in the last five years, another centre of minimum intensity has emerged in the southwest of Africa, very close to where the Willowy was sailing.Apparently, this is a sign that the Earth is heading towards pole inversion, meaning the north and south magnetic poles will flip, which could cause ships whose course is established by simple or magnetic compasses to sail in circles without even realizing it.But boats like the Willowy use a gyrocompass, which is able to find true north using gravity and the Earth's axis of rotation instead of the magnetic north. However, if the gyrocompass fails, it could cause the same problem the tanker experienced.The gyrocompass was damagedIn the case of the circling ship, it was determined that the its primary gyrocompass was malfunctioning. And, upon discovering the malfunction, they were able to resume their journey using their secondary gyroscope along with a magnetic compass.The company that owns the ship described the error as 'an incidental breakdown' and said it would be repaired at the next port, where shore technicians could identify the cause of the failure.